Introduction
A painful hip can severely affect your ability to lead a full active life. Over the last twenty five years, major advancements in hip replacement have greatly improved the outcome of the surgery. Hip replacement surgery is becoming more and more common as the population of the world begins to age.

What Is a Hip Replacement?
Hip replacement, or arthroplasty, is a surgical procedure in which the diseased parts of the hip joint are removed and replaced with new, artificial parts. These artificial parts are called the prosthesis. The goals of hip replacement surgery include increasing mobility, improving the function of the hip joint, and relieving pain.

Who Should Have Hip Replacement Surgery?
People with hip joint damage that causes pain and interferes with daily activities despite treatment may be candidates for hip replacement surgery. Osteoarthritis is the most common cause of this type of damage. However, other conditions, such as rheumatoid arthritis (a chronic inflammatory disease that causes joint pain, stiffness, and swelling), osteonecrosis (or avascular necrosis, which is the death of bone caused by insufficient blood supply), injury, and bone tumors also may lead to breakdown of the hip joint and the need for hip replacement surgery.
In the past, doctors reserved hip replacement surgery primarily for people over 60 years of age. The thinking was that older people typically are less active and put less stress on the artificial hip than do younger people. In more recent years, however, doctors have found that hip replacement surgery can be very successful in younger people as well. New technology has improved the artificial parts, allowing them to withstand more stress and strain and last longer.
Today, a person’s overall health and activity level are more important than age in predicting a hip replacement’s success. Hip replacement may be problematic for people with some health problems, regardless of their age. For example, people who have chronic disorders such as Parkinson’s disease, or conditions that result in severe muscle weakness, are more likely than people without chronic diseases to damage or dislocate an artificial hip. People who are at high risk for infections or in poor health are less likely to recover successfully. Therefore they may not be good candidates for this surgery. Recent studies also suggest that people who elect to have surgery before advanced joint deterioration occur tend to recover more easily and have better outcomes.

Why Do People Have Hip Replacement Surgery?
For the majority of people who have hip replacement surgery, the procedure results in:
• a decrease in pain
• increased mobility
• improvements in activities of daily living
• improved quality of life.

The Surgery
The hip joint is located where the upper end of the femur, or thigh bone, meets the pelvis, or hip bone. A ball at the end of the femur, called the femoral head, fits in a socket (the acetabulum) in the pelvis to allow a wide range of motion.

Hundreds of hip replacement surgeries have been performed in Tunisia and this operation has an excellent safety record. Some of the important steps in the operation are as follows:
General or local anaesthesia is utilized, so the patient is asleep throughout the procedure.
During a traditional hip replacement, which lasts from 1 to 2 hours, the surgeon makes two incisions the hip through the muscles and removes the diseased bone tissue and cartilage from the hip joint, while leaving the healthy parts of the joint intact. Then the surgeon replaces the head of the femur and acetabulum with new, artificial parts. The new hip is made of materials that allow a natural gliding motion of the joint
Before closing the incision, an xray (image) is made to make sure your new prosthesis is in the correct position.

The Artificial Hip Joint, called a prosthesis
The hip joint is located where the upper end of the femur, or thigh bone, meets the pelvis, or hip bone. A ball at the end of the femur, called the femoral head, fits in a socket (the acetabulum) in the pelvis to allow a wide range of motion
There are two major types of artificial hip joint:
(3D animation of artificial hip .flc animation file 1.9K zipped)
• Cemented Prosthesis
• Uncemented Prosthesis
Both types are widely used. The type of prosthesis used for your surgery is usually decided upon by your surgeon based on your age, your lifestyle, and the surgeon's past experience.
Each prosthesis is made up of two parts(image):
• The acetabular component, or socket portion, which replaces the acetabulum.
• The femoral component, or stem portion, which replaces the femoral head.
The femoral component (image) is made of a metal stem with a metal ball on the end. Some prosthesis have a ceramic ball attached to the metal stem. The acetabular component (image) is a metal shell with a plastic inner socket liner that acts like a bearing. The type of plastic used is very tough and very slick - so slick and tough that you could ice skate on a sheet of the plastic without much damage to the plastic.
A cemented prosthesis (image) is held in place by a type of epoxy cement that attaches the metal to the bone. An uncemented prosthesis (image) has a fine mesh of holes on the surface area that touches the bone. The mesh allows the bone to grow into the mesh and "become part of" the bone.

Is a Cemented or Uncemented Prosthesis Better?
The answer to this question is different for different people. Because each person’s condition is unique, the doctor and you must weigh the advantages and disadvantages.
Cemented replacements are more frequently used for older, less active people and people with weak bones, such as those who have osteoporosis, while uncemented replacements are more frequently used for younger, more active people.
Studies show that cemented and uncemented prostheses have comparable rates of success. Studies also indicate that if you need an additional hip replacement, or revision, the rates of success for cemented and uncemented prostheses are comparable.
The primary disadvantage of an uncemented prosthesis is the extended recovery period. Because it takes a long time for the natural bone to grow and attach to the prosthesis, a person with uncemented replacements must limit activities for up to 3 months to protect the hip joint. Also, it is more common for someone with an uncemented prosthesis to experience thigh pain in the months following the surgery, while the bone is growing into the prosthesis.

How to Prepare for Surgery and Recovery
People can do many things before and after they have surgery to make everyday tasks easier and help speed their recovery.
Before Surgery
• Learn what to expect.
• Arrange for someone to help you around the house for a week or two after coming home from the hospital.
• Arrange for transportation to and from the aeroport.
• Set up a “recovery station” at home. Place the television remote control, radio, telephone, medicine, tissues, wastebasket, and pitcher and glass next to the spot where you will spend the most time while you recover.
• Place items you use every day at arm level to avoid reaching up or bending down.
• Stock up on kitchen supplies and prepare food in advance, such as frozen casseroles or soups that can be reheated and served easily.
After Surgery
• Follow the doctor’s instructions.
• Work with a physical therapist or other health care professional to rehabilitate your hip.
• Wear an apron for carrying things around the house. This leaves hands and arms free for balance or to use crutches.
• Use a long-handled “reacher” to turn on lights or grab things that are beyond arm’s length. Hospital personnel may provide one of these or suggest where to buy one.

What Can Be Expected Immediately After Surgery?
You will be allowed only limited movement immediately after hip replacement surgery. When you are in bed, pillows or a special device are usually used to brace the hip in the correct position. You may receive fluids through an intravenous tube to replace fluids lost during surgery. There also may be a tube located near the incision to drain fluid, and a type of tube called a catheter may be used to drain urine until you are able to use the bathroom. The doctor will prescribe medicine for pain or discomfort.
On the day after surgery or sometimes on the day of surgery, therapists will teach you exercises to improve recovery. A respiratory therapist may ask you to breathe deeply, cough, or blow into a simple device that measures lung capacity. These exercises reduce the collection of fluid in the lungs after surgery.
As early as 1 to 2 days after surgery, you may be able to sit on the edge of the bed, stand, and even walk with assistance.
While you are still in the clinic, a physical therapist may teach you exercises such as contracting and relaxing certain muscles, which can strengthen the hip. Because the new, artificial hip has a more limited range of movement than a natural, healthy hip, the physical therapist also will teach you the proper techniques for simple activities of daily living, such as bending and sitting, to prevent injury to your new hip.

How Long Are Recovery and Rehabilitation?
Usually, people do not spend more than 8 to 10 days in the clinic after hip replacement surgery. Full recovery from the surgery takes about 3 to 6 months, depending on the type of surgery, your overall health, and the success of your rehabilitation.

What Are Possible Complications of Hip Replacement Surgery?
Hip replacement is one of the most successful orthopaedic surgeries performed. New technology and advances in surgical techniques have greatly reduced the risks involved with hip replacements.
The most common problem that may arise soon after hip replacement surgery is hip dislocation. Because the artificial ball and socket are smaller than the normal ones, the ball can become dislodged from the socket if the hip is placed in certain positions. The most dangerous position usually is pulling the knees up to the chest.
The most common later complication of hip replacement surgery is an inflammatory reaction to tiny particles that gradually wear off of the artificial joint surfaces and are absorbed by the surrounding tissues. The inflammation may trigger the action of special cells that eat away some of the bone, causing the implant to loosen. To treat this complication, the doctor may use anti-inflammatory medications or recommend revision surgery (replacement of an artificial joint). Medical scientists are experimenting with new materials that last longer and cause less inflammation. Less common complications of hip replacement surgery include infection, blood clots, and heterotopic bone formation (bone growth beyond the normal edges of bone). Studies are also looking at the use of bisphosphonates, ciprofloxacin, pentoxifylline, and other medications to prevent this bone resorption around the implants.

When Is Revision Surgery Necessary?
Studies have shown that more than 90 percent of people who have hip replacement surgery will never need to replace an artificial joint. However, because more people are having hip replacements at a younger age, and wearing away of the joint surface becomes a problem after 15 to 20 years, replacement of an artificial joint, which is also known as revision surgery, is becoming more common. It is more difficult than first-time hip replacement surgery, and the outcome is generally not as good, so it is important to explore all available options before having additional surgery.
Doctors consider revision surgery for two reasons: if medication and lifestyle changes do not relieve pain and disability, or if x rays of the hip show damage to the bone around the artificial hip that must be corrected before it is too late for a successful revision. This surgery is usually considered only when bone loss, wearing of the joint surfaces, or joint loosening shows up on an x ray. Other possible reasons for revision surgery include fracture, dislocation of the artificial parts, and infection.

What Types of Exercise Are Most Suitable for Someone With a Total Hip Replacement?
Proper exercise can reduce stiffness and increase flexibility and muscle strength. People who have an artificial hip should talk to their doctor or physical therapist about developing an appropriate exercise program. Most of these programs begin with safe range-of-motion activities and muscle-strengthening exercises. The doctor or therapist will decide when you can move on to more demanding activities. Many doctors recommend avoiding high-impact activities, such as basketball, jogging, and tennis. These activities can damage the new hip or cause loosening of its parts. Some recommended exercises are walking, stationary bicycling, swimming, and cross-country skiing. These exercises can increase muscle strength and cardiovascular fitness without injuring the new hip.